A microfiche appendix containing 375 frames on one card and is included in this specification and is hereafter referenced to as Appendix A.
(a) Field of the Invention
The present invention relates generally to orbital transfer, and more particularly, to an apparatus and method of translating a spacecraft from an inclined, eccentric orbit to a geostationary orbit in a time efficient manner while minimizing the energy required for the orbital transfer.
(b) Description of Related Art
Several general orbit transfer strategies are presently used for placing a spacecraft into a geostationary orbit. These methods are based on the classical generalized Hohmann transfer strategies that have been shown to be optimal in the context of the two-body problem. Other strategies for translating a spacecraft from an injection orbit to a geostationary orbit are disclosed in Spitzer U.S. Pat. No. 5,595,360, the entirety of which is hereby incorporated by reference.
This invention is directed to an apparatus and method for translating a spacecraft from a geosynchronous, inclined, and eccentric orbit to a geostationary orbit. The apparatus includes a propulsion thruster oriented on the spacecraft to generate a thrust having a predetermined force on the spacecraft. The apparatus further includes a controller for controlling the direction and timing of firing the propulsion thruster.
The controller includes means for calculating optimal direction and timing of firing of the propulsion thruster to translate the orbit of the spacecraft from the initial transfer orbit to the geostationary orbit utilizing a nonlinear parameter optimization algorithm.
In accordance with one aspect of the present invention, a method is provided for transferring a satellite from a initial orbit about the earth, the initial orbit having a first period inclination and a first eccentricity, to a final orbit about the earth, the final orbit having a second period inclination and a second eccentricity. The method comprises the steps of calculating an estimate of thrust vectors and burn times for an optimal two-burn orbit transfer from the initial orbit to the final orbit, using a non-linear root finding algorithm and computing thrust vectors and burn times for an optimal multi-segment orbit transfer from the initial orbit to the final orbit.
The invention itself, together with further objects and attendant advantages, will be best understood by reference to the following detailed description, taken in conjunction with the accompanying drawing.